A data center typically houses a plurality of appliances such as servers, computers, processors, routers, switches, and other electronic devices. Such a center may support one large user, such as a nationwide bank, or many users, each of which may need only one or a few appliances to support its business. The continued expansion of the use of computers and the Internet has led to construction and use of more and more data centers, each of which may house hundreds of appliances. As the number of appliances in a data center has increased, and each appliance has become more complex, effective management of these appliances has become a critical factor in the successful operation of the data center.